This invention relates to a vehicle window glass antenna for receiving broadcast waves, which is made up of conductive strips attached to the window glass in a suitable pattern. The antenna is particularly suited to automobiles.
In recent automobiles there is a trend to adoption of a so-called window glass antenna for receiving broadcast waves. In most cases the window glass antenna is provided in the rear window glass and is constructed of conductive strips disposed on the glass surface in a suitable pattern. The antenna is located in a relatively narrow space left above an array of defogging heater strips. Usually the conductive strips used as the antenna elements are electrically independent of the heater strips.
With an automobile window glass antenna of the above described type, it is difficult to receive FM radio broadcast waves and television (TV) broadcast waves with sufficiently high gains mainly because of the narrowness of the space which the antenna is allowed to occupy. As a countermeasure it is known to make an electrical connection between the antenna strips and the heater strips to utilize the heater strips as auxiliary antenna elements, and vice versa. However, this measure has a disadvantage that during defogging operation intrusion of considerable noise into the received signal is inevitable.
Also it has been developed to provide the windshield of an automobile with an antenna using either conductive strips or a transparent and conductive film. In this case it is possible to receive radio broadcast waves with relatively high gains since the antenna is allowed to occupy a relatively broad area.
Recently there is an increasing demand for an automobile window glass antenna which can efficiently receive both FM radio broadcast waves and TV broadcast waves, but thus far such a demand has not been met. That is, on an automobile window glas, even in the case of the windshield, it is very difficult to provide an antenna which exhibits high gains over a very wide range of frequency including both the VHF band (90-222 MHz) and the UHF band (470-770 MHz) used for TV braodcasting.